Phosphoramidothioates

ABSTRACT

Phosphoramidothioates of the general formula WHERE R is alkyl and R&#39;&#39; is an aromatic group such as substituted phenyl, naphthyl, pyridyl, or oxadiazolyl, useful as nematicides, are prepared for example, by reacting an 0,0-diakyl isopropylphosphoramidothioate with a compound of the formula R&#39;&#39;CH2Cl.

States Patent 1 Fan [ Dec. 24, 1974 IPIIIOSIPIHORAMIDOTHIOATES [75] Inventor: Hsing Y. Fan, Modesto, Calif.

[73] Assignee: Shell Oil Company, Houston, Tex.

[22] Filed: May 15, 1972 [21] Appl. No.: 253,031

[56] References Cited UNITED STATES PATENTS 2/1961 Schrader 260/959 X 3,019,250 1/1962 Kayser et al. 3,711,582 l/l973 Schrader et al 260/959 X FOREIGN PATENTS OR APPLICATIONS Germany Primary ExaminerLorraine A. Weinberger Assistant Examiner-Richard L. Raymond [5 7] ABSTRACT Phosphoramidothioates of the general formula where R'is alkyl and R is an aromatic group such as substituted phenyl, naphthyl, pyridyl, or oxadiazolyl, useful as nematicides, are prepared for example, by reacting an 0,0-diakyl isopropylphosphoramidothioate with a compound of the formula RCH CI.

4 Claims, No Drawings 1 PHOSPHORAMIDOTHIOATES FIELD OF THE INVENTION ,.The insecticidal use of certain S-benzyl phosphoramidothioates is disclosed in U.S. Pat. Nos. 2,971,020 and 3,019,250. I

Phosphoramidothioates' substituted by both an S- aralkyl group and an N-isopropyl group are not known from the literature.

SUMMARY. OF THE INVENTION It has now been found that phosphoramidothioate derivatives substituted by an S-aralkyl group and an N- isopropyl group are nematicidal compounds with outstanding properties.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The novel compounds of this invention are phosphoramidothioates of the following formula wherein R is alkyl of one to five carbon atoms, such as methyl, ethyl, propyl, isobutyl, or tert-amyl, and R is aromatic. By aromatic is intended a ring system which is aromatic in character, i.e., earbocyclic or heterocyclic.

Typical aromatic groups contemplated for use within the scope of this invention are oxadiazolyl, optionally substituted by alkyl of one to six carbon atoms, benzothiazolyl, thienyl optionally substituted by one or more halogens of atomic number 9-35, 5-hydroxy-4-oxo- (4H)-pyranyl, furfuryl, pyrimidinyl optionally substituted by one or more halogens of atomic number 9-35, thiazolyl optionally substituted by one or more halogens of atomic number 9-35, phenyl substituted by one or more of the following groups: halogen of atomic number 9-35 (that is, fluorine, chlorine, or bromine), cyano, alkylthio of one to five carbon atoms, such as methylthio, ethylthio, and propylthio, alkyl of one to five carbon atoms, such as methyl, ethyl, or isopropyl, halomethyl, such as trifluoromethyl, or alkoxy, such as methoxy, ethoxy, or propoxy, and naphthyl or naphthyl substituted by one or more halogens of atomic number 9-35, or pyridyl.

Particularly nematicidally active compounds of this invention are described by Formula I wherein R is methyl or ethyl and R is naphthyl, chlorophenyl, dichlorophenyl, methylthiophenyl, fluorophenyl, trifluoromethylphenyl, methylchlorophenyl, 5-chloro-2- thienyl, or 2,5-dichloro-3-thienyl, pyridyl, or oxadiazolyl.

In the most preferred class of compounds, having very high nematicidal activity, R is fluorophenyl, trifluoromethylphenyl, chlorophenyl or dichlorophenyl.

Typical members of this class of nematicides thus include O-ethyl S-(3-methyl-4-(methylthio)benzyl) isopropylphosphoramidothioate O-methyl S-( l-fluoro-2-naphthylmethyl) isopropylphosphoramidothioate O-ethyl S-( 4-bromophenyl) isopropylphosphoramidothioate O-methyl S-( I-bromo-Z-naphthylmethyl) phoramidothioate.

The phosphoramidothioates of the invention are readily prepared by combining an 0,0-dialkyl phosphoramidothioate with an active chlorine-containing compound as in the following reaction:

isopropylphosoHmoHNH-i -s-omw The active chlorine-containing compound contemplated for use in this process is a compound wherein the reactivity of the chlorine is increased by the resonant character of the group to which it is attached. The reaction is carried out at a temperature of from about to about C for a period of about 6 to about 72 hours. The product is isolated by one of the usual methods used by those skilled in the art, for example, by distillation or by recrystallization.

Some of the phosphoramidothioates may be prepared foilowing a reaction procedure similar to that taught in U.S. Pat. No. 3,019,250 wherein an alkali metal salt of an N-alkylthiolophosphoramidic acid is treated with an alkyl halide.

Some of the preferred methods for preparing these compounds are illustrated in the following examples. In the examples below, the structure of all the products was confirmed by elemental and spectroscopic analyses.

EXAMPLE 1 S-( 2-chlorobenzyl) .chlorobenzyl) isopropylphosphoramidothioate melting at 52-55 C. Yield: 87 per cent of theoretical.

EXAMPLES 2-16 Using the method of Example 1, the phosphoramidothioates described in Table l were prepared. In Examples 7 and 8, the product was isolated by distillation.

TABLE I PHOSPHORAMIDOTHIOATES PREPARED from 0,0-DIETHYL ISOPROPYL- PHOSPHORAMIDOTHIOATE AND AN ARYLMETHYL CHLORIDE benzyl) isopropylphosphorumidothioate PHOSPHORAMIDOTHIOATES PREPARED from (1.0-D1ETHYLISOPROPYL- PHOSPHORAMlDOTHlOATE AND AN ARYLMETHYL CHLORIDE Example Phosphoramidothioate Boiling Point or Yield. Number Melting Point.C. percent 3 O-ethyl S-(4-chlorobenzyl) 52-53 67 isopropylphosphoramidothioate 4 cthy1 S-(3.4-dichlorobenzyl) 58-59 41 isopropylphosphoramidothioate 5 O-ethyl S-(2,6-dichlorobenzyl) l04-l05 SO isopropylphosphoramidothioate 6 O-ethyl S-(naphthylmethyl) 64--65 16 isopropylphosphoramidothioate 7 O-ethyl S-(4-methylhenzyl) 150-152 63 isopropylphosphoramidothioate at 0.05 tnrr.

ll O-ethyl S-(3-chloro-4-methyl- 162 56 benzyl) isopropylphosphorat (1.1 tnrr. amidothioate 9 O-ethyl S-(3-trifluoromethyl- 40-42 40 benzyl) isopropylphosphoramidothioate 10 O-ethyl S-(2-rnethylbenzyl) 62-63 50 isopropylphosphoramidothioate l1 O-ethyl S-(Z-fluorobenzyl) 48-50 34 isopropylphosphoramidothioate l2 O-ethyl S-(3-fluorobenzyl) 43-44 38 isopropylphosphoramidothioate l3 O-ethyl S-(4-fluorobenzyl) 61-62 40 isopropylphosphoramidothioale l4 O-ethyl S-((2-chlorothiazol- 93 4-yl)methy1) isopropylphosphoramidothioate O-elhyl S-((2.5-dichlorothiazol- 50 4-yl)methy|) isopropylphosphorantidothioate 16 O-ethyl S-(3-(2.5-dichloro) 65-66 34 thenyl) isopropylphosphoramidothioate EXAMPLE l7 isopropylphosphoramidothioate Preparation of O-ethy| s (4 cyanobenzyl) A solution of 3.92 grams (0.02 mole) 4-cyanobenzyl isopropylphosphoramidothioate a. preparation of potassium O-ethyl isopropylphosphoramidothioate To a stirred solution of 105.5 grams (0.5 mole) of 0,0-diethyl isopropylphosphoramidothioate in 470 milliliters dimethyl sulfoxide was added portionwise 56 grams (0.5 mole) of potassium tert-butoxide over a period of 2-3 minutes. The reaction mixture was heated on a steam bath for 8 days and then evaporated under high vacuum to remove the solvent and any volatile compounds formed during the reaction. The product was 130 grams of a gummy solid, of which 123 grams was extracted twice with boiling hexane and the residue was dissolved in benzene. The solid which separated on standing was filtered off and the solvent was removed from the filtrate to give 88 grams of a tacky solid to which ethanol was added to give a 50 per cent solution of crude potassium O-ethyl isopropylphosphoramidothioate.

b. Preparation of O-ethyl S-(4-cyanobenzyl) grams bromide and 12 grams of potassium O-ethyl isopropylphosphoramidothioate in 50 milliliters ethanol (prepared above) was heated for 5 hours at 45 C. The reaction mixture was filtered and the filtrate was concentrated to dryness. The residue was mixed with methylene chloride and filtered. The filtrate was again concentrated to dryness to give a liquid residue that partially crystallized on standing. The crystals were filtered and washed several times with ether to give 1.6

of colorless, crystalline O-ethyl S-(4- cyanobenzyl) isopropylphosphoramidothioate, melting point 8284 C.

EXAMPLES 18-23 Using the method described in Example 17, the phosphoramidothioates described in Table 11 were prepared. The compounds were prepared in liquid form and purified by chromatography with the exception of compound No. 22 which is a solid.

TABLE ll PHOSPHORAMIDOTHIOATES PREPARED FROM POTASSIUM O ETHYL lSOPROPYL PHOSPHORAMlDOTHlOATE AND THE CORRESPONDING ARYLMETHYL CHLORIDE benzyl) isopropylphosphoramidothioate TABLE 11: Continued O-ETHYL ISOPROPYL PHOSPHORAMIDOTHIOATE AND THE CORRESPONDING ARYLMETHYL CHLORIDE Example Phosphoramidothioate Yield Number Melting Point.C. percent 19 O-ethyl S-(5-chloro-2- 60 thenyl) isopropylphosphoramidothioate 20 O-ethyl S-(4-pyridyl- 36 methyl) isopropylphosphoramidothioate 21 O-ethyl S-(benzothiazol- 2-yl-methyl) isopropylphosphoramidothioate 22 O-ethyl S-(4,6-dichloro- 105 pyrimidinQ-ylmethyl) isopropylphosphoramidothioate 23 O-ethyl S-(1,2,4-oxa- 90 diazol-3-yl-methyl) isopropylphosphoramidothioate EXAMPLE 24 S-(4-chlorobenzyl) methyl isopropylphosphoramidothioate (prepared in a) above) and 3.2 grams (0.02 mole) p-chlorobenzyl chloride in milliliters ethanol was heated to 50 C and held for 7 hours. The reaction mixture was filtered to remove salt, stripped of solvent and diluted with methylene chloride. The solution was filtered to remove an additional small amount of salt and again stripped of solvent. The oily residue was recrystallized from hexane to yield 5.3 grams of colorless O-methyl S-(4- chlorobenzyl) -isopropylphosphoramidothioate, melting point 69-70 C.

Yield: 90 per cent of theoretical.

EXAMPLES 25-56 Using the method of Example 24, the phosphoramidothioates described in Table III were prepared.

TABLE in PHOSPHORAMIDOTHIOATES PREPARED FROM SODIUM O-METHYL ISOPROPYLPHOSPHORAMIDOTHIOATE AND AN ARYLMETHYL CHLORIDE Example Phosphoramidothioate Melting Point.C. Yield, Number percent 25 O-methyl S-(2,4-dichloro- 80-8l 83 benzyl) isopropylphosphoramidothioate 26 O-methyl S-(4-methylbenzyl) 38-40 76 isopropylphosphoramidothioate 27 O-methyl S-(2-chlorobenzyl) 46-48 75 isopropylphosphoramidothioate 28 O-methyl S-(3,4-dichloro- 62-63 83 benzyl) isopropylphosphoramidothioate 29 O-methyl S-(4-methylthio- 88-91 69 benzyl) isopropylphosphoramidothioate 30 O-methyl S-( l-napthylmethyl) 64-65 87 isopropylphosphoramidothioate 3] O-methyl S-(4-cyanobenzyl) 95-96 88 isopropylphosphoramidothioate 32 O-methyl S-(2,6-dichlorolOO-lOl 76 benzyl) isopropylphosphoramidothioate 33 O-methyl S-(3-chloro-4-methylliquid 87 benzyl) isopropylphosphoramidolhioate 34 O-methyl S-(4-methoxyhenzyl] -67 isopro ylphosphoramidothioate 35 O-mel yl S-(4-fluorohcnzyl) 49-57 44 isupro iylphosphorumidotliioute .10 (Mme-thy! S-(Lmuthylhennl) 54-55 (7 isoprogylphosphormnidothiontu 37 O-mct yl S-(3-l'luorobenzyl) 72-73 58 isopropylphosphoramidolhioate 3H O-methyl S-(2-lluorohcnzyl) 54-55 55 isopropylphosphoramidothioale benzyl) isopropylphosphoramidothioale TABLEllL-Continued PHOSPHORAMlDOTHlOATl-LS PREPARED FROM SODIUM O-ME'I'HYL ISOPROPYLPHOSPHORAMlD'OTHlOATE AND AN ARYLMETHYL CHLORIDE Il-ylmethyl) isopropylphosphoramidothioate 47 O-methyl S-(benzothiazol-Z- 79-81 68 ylmethyl) isopropylphosphoramidothioate 48 O-methyl S-(S-chloro-Z-thenyl) 92 isopropylphosphoramidothioate 49 O-methyl S-(2,5-dich|oro-3 90 thenyl) isopropylphosphoramidothionte 50 O-methyl S-(4-pyridyl-methyl) 64-65 38 isopropylphosphoramidothioate 5| O-methyl S-(5-hydroxy-4-oxoll8-l I9 68 (4H)-pyran-2-yl-methyl) isopropylphosphoramidothioate 52 O-methyl S-furfuryl iso- 80 propylphosphoramidothioate 53 O-methyl S-(Z-pyridyl- 83 methyl) isopropylphosphoramidothioate 54 O-mcthyl S-((5-methyl-l.2.4- 87 oxadiazol-J-yllmethyl) isopropylphosphoramidothioate 55 O-methyl S-((2-chlorothiazo|- 70 t 4-yl)methyl)isopropylphosphoramidothioate 56 O-methyl S-((2,5-dichloro- 60-71 83 thiazoI-4-yltmethyl) isopropylphosphoramidothioate The isopropylphosphoramidothioates of this invention were thoroughly mixed in varying concentrations tion have been found to be effective in the protection with soil infested with the root-knot nematode Meloidoof plants from the harmful effects of nematodes that gyne incognita Acrita. Using standard procedures, the is, unsegmented roundworms of the Class Nematoda. efficacy of the isopropylphosphoramidothioates in conalso known as eelworms, which customarilyinhabit soil trolling root-knot nematodes in tomatoes was deterand feed upon the roots of plant growing therein Th mined as compared to an untreated control. Two tests isopropylphosphoramidothioates are particularly effecwere run; one in which the treated soil was held for 2 tive against root-knot nematodes ofthe genus Meloidoweeks b f re planting the tomato seeds and one in gyne. 50 which the soil was held 4 weeks. The dosages used and the per cent control of nematodes obtained at each EXAMPLE 57 dosage of each of the test compounds are set out in The isopropylphosphoramidothioutes of the inven- Table IV.

TABLE IV PER CENT CONTROL OF ROOT-KNOT NEMATODES Compound Dosage rate, parts per million 2-week Hold Time 4-week Hold Time O-methyl S-(2.4-dichlorohenzyl) I00 I00 I00 86 I00 I00 96 57 isopropylphosphoramidothioate O-mcthyl S-(4-ChlorobenZyl) I00 100 I00 96 I00 I00 I00 86 isoprogylphosphoramidothioate Omet yl S-(4-melhylbenzyl) I00 l00 64 I4 I00 82 96 6| isopropylphospliorulnidolhiontc O-mcthyl S-(Z-chlorohciuyl) I00 Hill 93 7| I00 I00 m 57 isoprofiylphusphornmidolhiunlc ()-mt:l tyl S-l3.4-tlichlurolwnxyll I00 lllll I00 an I00 I00 K! I) isopruflylphosphnrnmidothioutc O-mcl yl S-ld-mclhylthiohenzyl) I00 I00 89 64 I00 [00 Ho 50 isoprogylphosphoramidothiontc Q-mct yl S-( l-naphthylmelhyl) 100 )6 29 I4 I00 )6 ll 21 Eopropylphosphoramidothioate The isopropylphosphoramidothioates of this invention may, if desired, be applied as such to the locus to be treated. Ordinarily and preferably, however, these compounds are used in combination with an inert diluent or carrier to make it easier to measure accurately and to apply evenly the small amounts of the nematicide that are required to control nematode activity as well as to apply them in a form that will be readily dispersed through the soil. These compounds can be mixed with or deposited upon inert particulate solids, such as fullers earth, talc, diatomaceous earth, natural clay, kaolin, walnut shell flour, and the like, to form dry particular compositions. Such compositions may be employed as dusts, or they may, if desired, be dispersed in water with or without the aid of a surface-active agent. Alternatively, the dry compositions may be formed into granules or pellets by known techniques.

The isopropylphosphoramidothioates may be dispensed in the form of solutions or dispersions in inert organic solvents or in mixtures of inert organic solvents and water. The solvents that may be used in the preparation of these compositions include both polar and non-polar aliphatic and aromatic solvents including, for example, benzene, toluene, xylene, naphtha, nitrobenzene, dimethylformamide, carbon tetrachloride, acetone, methyl ethyl ketone, ethanol, propanol, butanol, dioxane, and mixtures thereof.

where R is alkyl of one to five carbon atoms; and R is naphthyl, or phenyl substituted by one or more substituents selected from halogen and alkyl of one to five carbon atoms or by halomethyl.

2. O-ethyl S-( 2-chlorobenzyl) isopropylphosphoramidothioate.

3. O-ethyl S-(4-chlorobenzyl) isopropylphosphoramidothioate.

4. O-ethyl S-(2,4-dichlorobenzyl) isopropylphos- 

1. ISOPROPYLPHOSPHORAMIDOTHIOATES OF THE FORMULA
 2. O-ethyl S-(2-chlorobenzyl) isopropylphosphoramidotHioate.
 3. O-ethyl S-(4-chlorobenzyl) isopropylphosphoramidothioate.
 4. O-ethyl S-(2,4-dichlorobenzyl) isopropylphosphoramidothioate. 